bobby150

Help! I've got a late 1995 150 with a 302. For the past year it has had what I've narrowed down to an ignition miss that I cannot figure out. I've had 2 veteran mechanics look at it and not be able to figure it out. Essentially, the engine bucks or misses when it in low to midrange rpm and under a load. (There's a jump in the voltage to the TPS at 2.2, which seems to be causing the miss). I've replaced or tested all ignition related parts, including the Throttle position sensor. All other sensors are operating as they should. I've replaced vacuum lines, you name it. I have not replaced the ECU, which I'm thinking is my next attempt. Please help with any ideas or suggestions! It's been going on over a year and drives me nuts!

Chris_1

iTrader: (1)

You have a jump in the voltage on the TPS that seems to be causing the miss.
What's your question ?
Lots of writeups online on how to change the TPS. Motorcraft only on that one.

bobby150

.

I was hoping that would be the case, but after replacing it with Motocraft, and dialing it in, I'm still getting a miss. The same as before. Any other ideas? I'm leaning toward the computer...

fltdriver

Pull your codes.

It very well could be a glitch with the ECU, before replacing though I would do some PMing on related components. Clean the TB, clean any connectors associated (TPS, injectors, IAC, etc..) as well as any chassis grounds in the engine bay, doesn't ever hurt to clean things up and even though they may not solve your current issue it may prevent something in the future. Ensure that you don't have vacuum leaks, if you still have the OEM plastic lines or older looking rubber replacements it would be best just to swap them out with new (I recommend these over regular rubber, http://www.siliconeintakes.com/silic...686d47fdf65361, 22ft of 4mm, also need a 4 way vacuum tee-available at auto/hardware store). Ensure that your cap/rotor are in good shape, test the PIP sensor in the distributor.

bobby150

Have done all of that, literally. Problem is its not throwing any codes. Have replaced the distributor and wires and plugs and all vacuum lines. Ran every test across the board. Checked and cleaned my ground. Just not sure what else it could be.

fltdriver

ECU and ICM would be the next two steps, though not sure if there is a way to test them or if they are just a replace and pray kind of deal. Best bet would be to find someone with same truck and swap one or the other to see if it changes.

bobby150

Oreillys can test the ICM, which I had done. And a mechanic I had look at it switched it out with one he had to be sure it wasn't that...not sure there's a way to test the ECU. But here's where it gets a little complicated...last year, when the problem started, I and a mechanic friend of mine thought the "miss" was the transmission slipping. And since I was wanting a 5 speed for hauling, we swapped the 4R70W for a ZF542 from a 250 with low miles. What we figured out is that it didn't solve the miss and may have made it worse.

So my problem as it relates to the ECU is that Ford didn't make an f150 with a 302 equipped with mass air flow that also had a 5 speed. They did in the Mustang. I've been told by 2 very experienced mechanics that I have an ignition miss. Before I go replacing the ECU, I'm trying to figure out whether there is any way to reflash the computer to work with a 5 speed, to see if that's the issue or not. Any advice or thoughts would be much appreciated.

fltdriver

What? I thought every engine/trans option on the 96 model has MAF? I know that's OBDII so it doesn't really help you. Pretty sure though that ford was all MAF in 95 as well, regardless of the trans.

bobby150

Right about obd11. All that I've been able to find are speed density. I bought a computer off eBay for a 95 150 with a 5 speed, but it is speed density...I believe they fully made the conversion in 96.